since my car is not street legal yet , I've only drove it around the block.. but I do start it up every week or two.. the last couple of times I've started it, smoke comes out of each tail pipe.. its not black smoke .... I read on the forum that it may be a bad modulator valve but I clamped the hose near the carb and still smokes. also, doesn't the pcv valve should come from a vacuum port on the intake? there's no vacuum coming from the hose, the other end of the hose down below the firewall.. there is a faint whistle coming from around the carb. I tightened the carb bolts but did not find the leak. I would appreciate any help on this... thanks!
Silly question, but has it been cold outside the last couple of times you started it? The vacuum leak you will need to spray around the carburetor with carb cleaner around both gaskets if the engine speed increases and seems to run better your leak is with your gaskets. You can also take some heater hose stick it to your ear and go around the carb so you can try to pin pount the exact location. As far as the PCV-Valve someone else should be able to help. Good luck!
Im sure hes reffering to the color of smoke, you mentioned its not black, is it grey, blue, white etc?
color of smoke its light colored, but can't tell exactly as its under the carport another issue I forgot to mention.. turning the idle mixture screws seems to make no difference when turning either way.. does the 72' have 2 vacuum lines running to C4?
it could be steam ? I let it run at least 15 minutes but it still did not clear up.. I put my hand about an inch from exhaust tip but did not get condensation or soot on my hand
Video example: [nomedia="http://www.youtube.com/watch?v=LYoT-fPWbt0"]2008 Mustang GT - FRPP Stingers, Kooks Longtubes Catted H, FRPP Hot Rod Cams - Cold Start - YouTube[/nomedia] Immediately after first start up, there is a quick puff of black from the passenger's side (rich on first fire, or carbon left over in the exhaust), then 1-2 seconds later reveals a slight hint of blue smoke (oil, from who knows what, but engine related), then within 5-7 seconds the chambers, manifolds and exhaust heats up and the steam starts going (normal). Does any of this look like what you have going on?
If the mixture screws have no effect when you turn em in/out...You have a vacuum leak. PCV is usually connected to base of carb at rear or directly to intake manifld at a vacuum port (large one) Also usually on back of intake. The smoke out the tail pipes could be simple condensation collecting in the exhaust.(Is it humid and cool down there yet??) If the car does not get up to operating temp and get driven, condensation will build up in the crank case and in the exhaust system and you will get pale grey/white smoke out the pipes till it cooks off. Have you noticed if the cooling system is loosing coolant (Level in radiator has dropped) BUt you cant find an external leak??? If so...You have an engine sealing issue allowing it to pump coolant into the cyl bores where it gets turned to steam and blown out the tail pipe. Does the exhaust smell like anti freeze???
smoke out of tailpipes so, it looks like I have a vacuum leak somewhere, the pcv valve is connected to a small metal tube leading down the firewall to the trans area... I checked the coolant level and its about an inch or 2 below the cap.. the smoke does not have an odor. could that mean its neither trans fluid or antifreeze?? we are starting to have chilly evenings lately. thanks for your help
The smoke you see is most likely condensation. Is the line with the PCV teed to feed vacuum to it and the modulator on the trans??? Plug the port that feeds the PCV and the trans (dont drive it this way) the trans wont shift. If your vacuum leak goes away...Follow the steel line down to the trans...Inspect its full length looking for a break/hole or bad rubber hose at the modulator. pull the hose at the modulator and see if there is tranny fluid in it...If so...Replace the modulator...Its diaphragm is perforated allowing the engine to suck trans fluid...(This will cause smoke out the tail pipe) Stinky smoke. It will also cause drivability issues since the engine is not designed to run on tranny fluid. You stated that you feel no suction at the PCV valve with the engine running...This points to a gross vacuum leak as well. It could be an intake gasket (At head/intake interface) Carb base gasket...Disconnected/broken vacuum hoses... Disconnected/perforated PCV hose...Does the car have power brakes...If so, the vacuum booster may actually be causing the vacuum leak. (look for a rust hole on the booster housing/may be hard to locate) I have seen em rust through on the back side facing the firewall as well as behind the master cyl mount point. Use water in a squirt bottle to find vacuum leaks (it will cause a definite stumble when it gets sucked in at the leak point) Dont use starting fluid or any other flammable substance to check for vacuum leaks since they may (in a spectacular fashion) indicate its time for new spark plug wires and or a distributor cap. Not to mention you will need new forearm hair and eyebrows...Good luck!!!
vacuum leaks I believe you are right about being condensation.. the smoke/steam really don't have much of an odor... the pcv valve hose was connected to a metal tube leading down the firewall. this hose have no vacuum and I have yet to trace it to other end.. the modular valve has its own tube, don't know if it has vacuum but when I drove it around the block, it did shift... I need to connect the pcv to the correct vacuum port and will also have to try and find the vacuum leaks. Thanks for all the help you guys!!
gasoline in the oil Well, I found out what is making the smoke out of the tailpipe. gas in the oil.I was changing the oil yesterday and a gallon or 2 of gas came out with the oil not sure how the gas is getting there but I notice that my fuel level drops pretty fast.. I have an electric fuel pump and dropped the pressure from 6.5 lbs to 4.5lbs, not sure if that will help hoping it was the carb that could not handle that much fuel pressure.. its a Holly 4barrel double pumper but not the kind with the removable bowls. looks like the whole top has to come off on a good note, I figured out the vacuum issue... the carb/intake gaskets
